What is conjunctivitis?
The conjunctiva is a thin, moist and shiny tissue that is partially located under the inside of the eyelids. Here it distributes the tear fluid on the surface of the eye like a soft cloth. To be able to see the conjunctiva, the eyelid must be folded back, for example by placing it around a thin rod. If the conjunctiva is inflamed, it also makes itself felt: by itching, burning and producing red eyes.
Conjunctivitis is one of the most common eye conditions. It can affect people of all ages, but children are more at risk than adults because their immune systems are not yet fully mature. According to a rough estimate, more than 100,000 people in Switzerland suffer from conjunctivitis every year.
Inflammation of the conjunctiva can have various causes. It depends on them whether the conjunctivitis is contagious or non-contagious.
Causes: How does conjunctivitis develop?
An inflamed conjunctiva swells and releases proteins and white blood cells (leukocytes). It is usually microorganisms such as viruses or bacteria that cause conjunctivitis. In these cases, the disease is infectious, so there is a risk of infection. Causes that result in a non-infectious form of conjunctivitis are less common.
Infectious conjunctivitis
In adults, conjunctivitis is mainly triggered by viruses, for example adenoviruses or herpes viruses. In babies and children, however, conjunctivitis is more likely to be caused by bacteria, including staphylococci, streptococci, pneumococci or chlamydia. The number of possible bacterial and viral pathogens of conjunctivitis is large. In rare cases, parasites (e.g. demodex mites or threadworms) can also trigger infectious conjunctivitis.
There are numerous transmission routes for infectious conjunctivitis. Here are some examples:
- Sometimes those affected rub their itchy or burning eyes due to conjunctivitis. If the pathogens get onto the hands and from there onto objects, other people can become infected.
- When speaking, sneezing or coughing, there is a risk that sufferers will pass on conjunctivitis to others through droplet infection.
- If you wear contact lenses, you should pay meticulous attention to clean containers, and if you use eye drops, make sure they are sterile. Otherwise, conjunctivitis pathogens (Pseudomonas bacteria) could accumulate in the fluids.
- Newborn babies may become infected with conjunctivitis pathogens in the birth canal of a mother suffering from conjunctivitis.
Non-infectious conjunctivitis
There are also many possible causes of inflammation of the conjunctiva, which are not contagious but nevertheless have unpleasant effects:
- External stimuli can damage the sensitive eyes and trigger conjunctivitis. Examples of such irritations are dirt, dust, smoke, chlorinated water, draughts and injuries (burns, scalds).
- Allergies to pollen, medication or other allergens often cause eye irritation and can result in conjunctivitis.
- A lack of tear fluid can lead to dehydration of the surface of the eye and to tissue damage or conjunctivitis. It is medically known as keratoconjunctivitis sicca.
- Fungi (e.g. Aspergillus or Candida) can also cause conjunctivitis in rare cases. People with a weakened immune system are particularly at risk.
Symptoms: How does conjunctivitis manifest itself?
The typical symptoms of conjunctivitis include red eyes. They often burn or itch, and moving the eyelids can be painful. Some sufferers react sensitively to bright light. In addition to increased lacrimation, the eyes often secrete a purulent, sticky secretion that can lead to temporary blurred vision. Many sufferers complain of clogged eyes, especially in the morning after waking up.
Because of its characteristic reddening of the eye, conjunctivitis is sometimes also called “pink eye”. The red coloration of the eyes is caused by increased blood circulation and the protrusion of the conjunctival blood vessels.
Conjunctivitis can lead to complications that cause further symptoms. For example, inflamed eyelids and swollen lymph nodes.
Diagnosis: How do you recognize conjunctivitis?
If you are suspected of having conjunctivitis, your doctor will first examine your eyes carefully. Perhaps with the help of a slit lamp; this instrument can be used to illuminate different areas of the eye and assess them in detail in a highly magnified view. Possible aspects include injuries and swelling as well as the type of secretions secreted by the eye. The nature of the secretions can indicate whether conjunctivitis is caused by viruses or bacteria – an important distinction because the two groups of pathogens require different treatments.
A rapid antigen test following a swab of the conjunctiva can show whether the sample taken contains adenoviruses, which are particularly infectious. Your doctor may also have a sample of the infected secretion examined in a laboratory. This determines exactly which pathogen has caused the conjunctivitis. This can be important to find out whether you may be suffering from a particular form of conjunctivitis.
Some of these conjunctivitis cases are particularly unpleasant:
- Trachoma is an inflammation of the conjunctiva caused by certain bacteria (Chlamydia trachomatis) that affects both eyes. Although this infection, known as inclusion conjunctivitis, is rare in Europe, it is the most common eye disease worldwide. It can lead to blindness and should be treated at an early stage.
- Gonococcal conjunctivitis is a purulent conjunctivitis with a risk of corneal damage. It can impair vision and, if left untreated, can cause symptoms including blindness.
- Koch-Weeks conjunctivitis is a mucopurulent form of conjunctivitis that occurs mainly in the southern hemisphere. It is very contagious.
- Ocular pemphigoid is an autoimmune disease that can cause conjunctivitis, in which the conjunctival tissue shrinks and scars. Older people are particularly affected.
Clinical picture: How does conjunctivitis progress?
The inflammation of the conjunctiva often begins in one eye. From here it can easily spread to the other eye, for example via the hands. If the symptoms of the disease occur suddenly and severely, but do not persist for too long, this is known as acute conjunctivitis. If the redness of the eyes or other symptoms last longer and are usually less pronounced, this is chronic conjunctivitis.
It usually takes five to twelve days from infection until the first symptoms of conjunctivitis appear – this is the incubation period. When the symptoms become noticeable, you should expect them to last for around seven to 14 days.
Even if the accompanying symptoms of conjunctivitis possibly subside on their own, which often happens, you should consult your doctor to be on the safe side. Complications are always possible and untreated conjunctivitis could have serious consequences. Or the course of conjunctivitis is unnecessarily prolonged. For example, in the case of inclusion conjunctivitis, which can last for months in unfavorable cases.
Therapy: What to do with conjunctivitis?
The treatment of conjunctivitis depends on the cause of the disease:
Treatment of bacterial conjunctivitis
If the conjunctivitis was caused by bacteria, ointments or eye drops containing an antibiotic can help.
Treatment of viral conjunctivitis
However, there are no causally effective medications against most of the viruses that can cause conjunctivitis. Treatment with antiviral eye drops or ointments is only possible for a few types of viruses that cause conjunctivitis (such as herpes viruses).
However, there are remedies with which your doctor can at least alleviate the annoying side effects of conjunctivitis. For example, eye drops containing cortisone can help with blurred vision or hypersensitivity to light. And you can soothe your eyes, which are irritated by conjunctivitis, by placing a warm (or cold) washcloth on them.
To avoid infecting other people – or catching the disease from someone who is ill – you should pay meticulous attention to hygiene. This includes, for example, frequently disinfecting your hands; it can also protect you from spreading conjunctivitis from one eye to the other. If you do not live alone, separate towels and washcloths are also important. Even when the symptoms of conjunctivitis have long since subsided – because some viruses can survive on plastic and metal surfaces for more than a month.
